Ports: Control; Ports: Fsk - microHAM DIGI KEYER Manual

The control channel is used by the host application to control transceiver frequency, mode, T/R switching
and many other parameters. The application communicates with the radio using a serial protocol. Most
modern radios implement some form of serial control but almost every radio implementation is different.
The amount of radio control depends on the particular application and radio.
TIP: The COM port number assigned in Router MUST match the port number assigned in the host
application. First configure the virtual COM ports in Router then configure the application.
When a COM port is assigned in the Router
but not in the application (or no application is
running) Router will show the channel as
closed.
When an application opens the COM port assigned for control (usually at start-up), Router shows the
channel as open and displays baud rate, data bits, parity and number of stop bits used by the applicaiton.
For example, 4800 8N2 means: 4800 baud, 8 bits data length, parity = none, and two stop bits.
TIP: If the application permits, always configure the Radio Control port to use two stop bits.
Communication is a little bit slower (9%) but more reliable. Some radios require two stop bits.
Data flowing thru the Control channel are indicated by two arrows. A green arrow indicates data flow from
the host application to the radio and a red arrow indicates data flow from the radio to the application.
The virtual COM port assigned for Control can be shared with CW and/or PTT but sharing must be
specifically supported by the application. Many applications do not know how to share the radio
port with other functions, use the control lines (RTS, CTS, DTR, DTS) for handshaking, or apply a
fixed level.
The FSK channel is used by the application program to send FSK keying signal. FSK is used primarily for
RTTY. It is very important to understand the difference between FSK and AFSK.
FSK is a digital (On/Off) signal from the computer serial port (or external modem). This signal is used in
the transceiver to generate a frequency shift. FSK must be supported by the transceiver (this mode is
commonly labeled RTTY or FSK).
AFSK is a analog signal generated by the computer sound card (or external modem) used in the
transceiver modulation circuits for operating digital modes as RTTY, PSK31, AMTOR etc. Computer
sound card generated AFSK or PSK does not require special transceiver support and can be used in the
LSB, USB or FM mode of the transceiver. Some radios have dedicated modes for AFSK (generally labeled
PKT or DATA) with special features.
It is very important to properly adjust the audio drive level of an AFSK system so as to not overdrive
the first transmit audio amplifier stage in the transceiver and produce a wide, distorted signal, full of
intermodulation products. It is important to appreciate that distortion generated at this point due to
overdrive CANNOT be reduced or eliminated by the reduction of the microphone gain control – it is
the signal level that must be adjusted to be about the same as would be expected from a microphone.
microHAM © 2006 All rights reserved
CONTROL PORT
FSK PORT
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